Helically wound tubing

ABSTRACT

A locked seam is formed in ducting formed by convoluted metal strip and seam locking adjacent edges of adjacent convolutions, in which one edge is folded to form a pair of inwardly facing channels and the other is folded to form a generally T-shaped flange and the arms of the T-shaped flange are locked within the channels. The seam may be formed by folding the edges of the strip before it is convoluted to provide along one edge an open U-shaped element facing out of the plane of the strip. A complementary flange is formed along the other edge, generally of similar U-shape or L-shape and after the strip is convoluted and the edges are mated the U-shape is deformed to form the seam. Apparatus for forming the seam comprises a mandrel removably mounted on a frame and two pairs of forming means disposed about the mandrel, one pair being fixed in its location relative to the frame and the other pair being movable with the mandrel, whereby the mandrel can be changed without requiring adjustment of the forming means.

nite States Patent [72] inventor John Massey Trihey Balwyn, Victoria,Australia [21 Appl. No. 865,275

[22] Filed Oct. 10, 1969 [45] Patented Nov. 23, 1971 [73] AssigneeJohns-Manville Corporation New York, N.Y.

[32] Priorities Oct. 17, 1968 [33] Australia May 12, 1969, Australia,No. 54863/69 [54] HELICALLY WOUND TUBING 6 Claims, 20 Drawing Figs.

[52] U.S.Cl. 138/154, 72/49 [51] a. F16l11/16 [S0] l38/l54, 150, I35,I36, 144; 72/49 56] References Cited UNITED STATES PATENTS 3,094,1476/l963 Nemer 138/154 X 3,435,852 4/l969 Trihey Primary Examiner- LaverneD. Geiger Assistant Examiner-Richard J Sher Allorney-Silverman & CassABSTRACT: A locked seam is formed in ducting formed by convoluted metalstrip and seam locking adjacent edges of adjacent convolutions, in whichone edge is folded to fonn a pair of inwardly facing channels and theother is folded to form a generally T-shaped flange and the arms of theT-shaped flange are locked within the channels The seam may be formed byfolding the edges of the strip before it is convoluted to provide alongone edge an open U-shaped element facing out of the plane of the strip.A complementary flange is formed along the 1 other edge, generally ofsimilar U-shape or L-shape and after the strip is convoluted and theedges are mated the U-shape is deformed to form the seam. Apparatus forforming the seam comprises a mandrel removably mounted on a frame andtwo pairs of forming means disposed about the mandrel, one pair beingfixed in its location relative to the frame and the other pair beingmovable with the mandrel, whereby the mandrel can be changed withoutrequiring adjustment of the forming means.

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ATTORNEYS PATENTEDNUV 23 1911 MMPQ \N PATENTEDNUV 23 1% sum 09 [1F 1oINVEN [OR domv Massey "Few/Er ATTORNEYS HELICALLY WOUND TUBINGBACKGROUND OF INVENTION l. Field of Invention The invention relates tothe formation locked seamed ducting of the US. Pat. No. 3,435,852.

2. Prior Art The ducting described in our said prior patent has provedmost satisfactory in use but, by virtue of its construction relativelycomplex machinery has been required to form the locked seam. Apparatusfor the production of the ducting is described in our prior U.S. Pat.application No. 638,393 and this apparatus comprises a mandrel having anumber of form ing and driving rollers arranged about its circumference,which apparatus operates to form the locked seam. This requires veryaccurate setting of the rollers and a further disadvantage of thisconstruction is that since each mandrel can be used to form one diameterof duct only, to change from one duct size to another necessitates thechanging of the mandrel and the adjusting of the positions of the manyforming rollers. In practice therefore we have found it necessary tochange the whole forming head when changing to a new duct size.Furthermore, the construction of the double locked seam according to ourprior application requires that in the initial stages of construction,the flange and channel from which the seam is formed having asubstantial depth and accordingly they are considerably stretched inbending about the mandrel. This creates particular problems if thematerial is not sufficiently ductile.

of helically wound general type described in prior SUMMARY The primaryobject of this invention is to provide a new form of locked seamconstruction which may lead to the simplification of the apparatusnecessary for its formation. A further object is to provide a method offorming a locked seam in which the major part of the formation of theseam can be carried out on the material in strip form before the edgesare brought together. In particular, it is the object to provide such amethod for use in the formation of helically wound ducting in which asubstantial part of the seam-forming operation can be carried out beforethe material is convoluted in the coiling head. The preferred form ofthe invention allows the fonnation and closing of the seam to beperformed almost entirely by the use of simple bending and pressingoperations avoiding any substantial drawing operation during theprocess. The preferred form of the invention also substantiallyeliminates buckling or wrinkling of the metal at the seam.

According to this invention there is provided a tube formed fromhelically wound ductile strip material with adjacent edges of the stripjoined together by a locked seam wherein said locked seam comprises apair of generally oppositely directly channels formed in one edge anddisposed on opposite sides of the longitudinal medial plane of the seamwith their mouths facing, and a complementary flange of generallyT-shaped cross section formed in the other edge with its arms disposedone within each of the said channels.

According to one form of the invention the channels are directly facingone another and the arms of the flange are substantially coplanar. Inanother form of the invention the channels are disposed so that theirdirections of facing intersect at an angle slightly less than l80 andthe arms of the flange are correspondingly angled. In this constructionthe channels are disposed to face slightly outwardly of the tube.

The invention further provides a method of forming helically woundseam-locked tubing from ductile strip material comprising the steps offorming in one edge of the strip at least one element of U-shaped crosssection and in the other edge at least one complementary flange,convoluting the strip and mating the adjacent edges of the convolutionsso that the flange lies within the U-shaped element, folding the or eachU- shaped element and the flange to form a pair of generally oppositelydirected channels and a pair of generally oppositely directed flangearms lying within the channels. and flattening the channels to grip theflange arms within them and form a locked seam.

A preferred method of forming the seam according to this inventioncomprises the steps of forming in one edge of the strip a U-shapedelement which is formed with an open mouth directed at right angles tothe general plane of the strip and outwardly of the formed tube, saidU-shaped element having an outer wall and an inner wall, the inner wallbeing formed by a deep corrugation or rib formed by folding the strip;forming in the other edge of the strip a similar deep corrugation or ribdisplaced from the edge of the strip to leave an edge flange;convoluting the strip, and mating the adjacent edges of the convolutedstrip so that the flange lies within the U-shaped element and the outerwall of said element lies within the rib of the flanged edge of thestrip, and bending the ribs inwardly towards each other to form theU-shaped element into a pair of inwardly facing channels and the flangein a flange of T- shaped cross section with the arms of the T lyingwithin the channels and flattening the channels so that the arms of theflange are locked within the channels and the outer wall of the channelis locked within the rib of the flanged edge.

In an alternative form of the invention the locked seam is formed byfirst folding one edge of the strip to form a U- shaped element with anopen mouth directed at right angles to the general plane of the stripand fomiing a complementary flange element in the other edge mating theedges, inwardly deforming the sidewalls of the U-shaped element to closethe mouth thereof so that the sidewalls of the element form with the webthereof two inwardly facing channels and the flange element is bent overon itself to a T-shaped configuration. and flattening the seam to lockthe arms of the flange within the channels.

The invention provides a still further method of forming the seamcomprising the steps of first forming in one of the edges of the strip apair of parallel U-shaped elements arranged side by side and in theother edge a pair of parallel flange elements arranged side by side,mating the flange elements within the U-shaped and spreading thechannels apart by bending them in opposite directions about thelongitudinal medial plane of the seam so that the U-shaped elements formtwo inwardly facing channels and the flange elements are substantiallycoplanar and form the arms of a flange of generally T-shaped crosssection with the arms lying within the channels, and flattening thechannels to lock the arms of the flange within the channels.

The invention also provides apparatus for forming helically wound tubingfrom ductile strip material comprising a frame, a mandrel mounted on theframe but removable therefrom and forming means located about theperiphery of the mandrel for seaming together adjacent edges of stripmaterial convoluted about the mandrel characterized in that the formingmeans comprise two cooperating pairs of forming means one pair beingmounted on the frame and the other pair being mounted so as to beremovable on removal of the mandrel whereby on substitution of one sizeof mandrel for another only one of the pairs of forming means needs tobe adjusted to accommodate the new mandrel. Preferably the mandrel is afixed substantially cylindrical mandrel and at least one of the formingmeans comprises a rotatable roller located in a cavity formed in themandrel.

The reference above to a flange" being formed on one edge of the stripis not to be understood as limiting the invention to the provision of aplan flanged edge. The expression flange" and channel" have been usedlargely for convenience of description and as will be apparent from thedescription of the embodiments of the invention the flanged edge of thestrip may be in fact constituted by a channel and be substantiallysimilar to the edge which is referred to as terminating in a channel.

In order that the invention may be better understood the preferredembodiment and a number of alternative constructions will now bedescribed by way of example and with reference to the accompanyingdrawings:

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a plan view of part of apparatusfor forming convoluted corrugated tubing by the method of thisinvention;

F I65. 2 to are cross-sectional views on the lines 22, 3- 3, 4-4, 5-5respectively of FIG. 1 and illustrate the steps in the formation of thestrip for use according to this invention;

FIG. 6 is a perspective view ofa section ofstrip according to theinvention;

FIG. 7 is a side elevation partly in cross section of the forming headshown in FIG. 1;

FIG. 8 is an end elevation partly in cross section of the forming head;

FIG. 9 is an enlarged cross-sectional view of the forming mandrel(broken away to reduce space);

FIG. 10 is a fragmental cross-sectional view of modification of theconstruction shown in FIG. 9;

FIG. 11 is a plan view to a small scale of a modification of theapparatus for producing small diameter ducting;

FIG. 12 is a cross-sectional view to a larger scale of the apparatus ofFIG. 11;

FIGS. I3 and 14 are enlarged fragmental views showing the stages in theformation of the seam in the apparatus of FIGS. 11 and 12',

FIG. 15 is a side elevation (from the opposite side to FIG. 7) of theforming head showing the arrangement ofthe tube spiking mechanism;

FIG. 16 is a cross-sectional view (on an enlarged scale) on the line16-16 in FIG. l5;

FIG. 17 is a fragmentary cross-sectional view showing a mandrel andforming mechanism for forming the seam by an alternative method;

FIG. 18 shows diagrammatically the stages in the formation of a seam bythe method employing the forming head of FIG. 17',

FIG. 19 shows diagrammatically yet another method of forming the seam ofthis invention; and

FIG. 20 shows diagrammatically how, using the method and apparatus ofthis invention mandrels of different size may readily be substituted onefor another on the one machine.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to FIGS. 1 to 5,ductile strip material, such as aluminum, 1 is formed to a corrugatedconfiguration (see FIG. 2) by corrugating rollers (not shown) and in thelast stages of its formation narrow edge ribs 2, 3 are formed by formingrollers 4. The strip then passes to another set of forming rollers 5 andthe ribs 2 and 3 are pushed in by crushing rolls 6, 7 to make the ribsdeeper and narrower.

The strip then passes to the next set of rolls 8 where the edge marginsof the strip are turned down so that channels 11, 12 are formed in eachedge. bounded respectively by downturned edge margins 13 and rib 2 andrib 3 and downturned edge margin 14. At the same time the bases of thechannels are indented by the forms 9, to form convexities 10.

The strip is then perforated by perforating head 15 and is passed overan initial forming roller 16 to the forming head 17 where it isconvoluted about mandrel 18 to form a tube 19.

As the strip is fed to the forming head 17 it passes between formingrolls 21, 22 and is coiled about mandrel 18 to a helical configurationwith the edges of the strip in mating relationship.

For convenience of description the channel 11 will be referred to as achannel element and the channel 12 which is narrower and fits within thechannel 11 will be referred to as a flange. As the strip is coiled aboutthe mandrel with the flange I2 lying in the channel element 11 it passesbeneath deforming rollers 23 which deform the ribs 2, 3 inwardly topartly close the mouth ofthe channel 11. A small backing roller 20 islet into the mandrel below the deforming rollers 23 to reduce friction.As the seam thus partly formed continues around the mandrel it againpasses between the forming rolls 2], 22 at a position where the rollsare shaped to complete the inward deformation of the ribs and to crushthe seam flat as shown in FIG. 9.

The final operation of closing the seam forms the flange to a generallyT-shaped configuration with the edge 14 squashed down to form one arm ofthe T and the rib 3 squashed in to form the other arm of the T and withthe shank of the T formed by the portion 3a of the rib 3. The two armsof the T are gripped in the inwardly facing channels formed by bendingover the edge margin I3 and the rib 2, and are held within thesechannels (see FIGS. 9 and 10).

The formation of the seam in the the operation described above wascarried out partly by the corrugating rolls and the crushing rolls 6, 7and thereafter the seam was completed by mating the edges of the stripand bending the ribs 2, 3 by means of the deforming rolls 23 and theforming rolls 21, 22. Thus it will be seen that all of the initial stepsin the formation of the seam are carried out before the two edges arebrought together and that after mating of the edges, only the steps ofbending in the ribs to form the two oppositely directed channels andpressing them down, are required to be performed. It will be observedalso that the double locked seam is formed from channels which are onlyhalf the height of that which would be necessary for the formation ofthe double locked seam of our prior application No. 5,601/66. Thus thereis substantially less stressing of the material in forming it about thecoiling head. Furthennore, in view of the fact that only two operationshave to be performed after the edges of the strip are brought together,these operations can be carried out with only two sets of formingrollers. Thus is is not necessary, as in the prior construction, toprovide a large number of rollers positioned about the circumference ofthe forming mandrel. Because of the very much simpler construction ofthe forming head it becomes a relatively simple matter to substitute oneforming head for another when it is desired to change from one tube sizeto another. This feature of the invention will be more fully describedhereinafter.

The provision of the convexities 10 in the bases of the channels has theeffect of eliminating wrinkling or buckling of the seam when the stripis convoluted about the mandrel. Without the convexity such wrinkling islikely to occur because of the distance of the mass of metal in the baseof the seam from the neutral axis of curvature. The provision of theconvexities reduces this effect. A further advantage derives from thefact that, as is best seen from FIG. 14, the flattening of the seamcauses the ribs to tend to straighten out the convexity and, due to itselasticity, the convexity tends to spring back thereby forming a tighterseam.

A slight modification of the seam above described is shown in FIG. 10 ofthe drawings. In that FIGURE convexities 10 in the channels are notformed and the end portions of the forming rolls 2], 22 are shaped sothat the final seam instead of being crushed flat is slightly bent aboutits longitudinal medial plane. This slight deformation of the seamalters the line of action of forces tending to open the seam andconsequently leads to a somewhat strongerjoint.

A further modification of the apparatus is shown in FIGS. 11 to 14. Thismodification is designed primarily for use in the manufacture of smalldiameter pipes say, of the order of 2 H2 inches to 3 inches diameter.For such pipes it is not possible to inset the forming roller 21 intothe bottom of the mandrel and also because ofincreased resistance tobending over the small diameter it is desirable for the deformingrollers 23 to be driven to help clear the tube from the mandrel. In thismodification the forming roll 21 is omitted and the deforming rollers 23are placed by a driven grooved forming roll 23A provided with a V-groove30 to inwardly deform the ribs 2 and 3. Flattening down of the seam isdone by a plain roller 31 provided at the end of the mandrel. As will beseen from FIG. 11, the roller 22, the mandrel l8 and the roller 23A areeach arranged with respect to one another at an angle equal to the helixangle of the tube. The flattening roller 31 is however mounted on anaxis parallel to that of the roller 22 with which it cooperates.

In another modification the mandrel 18 may be rotatable.

FIGS. 15 and 16 show in some detail the spiking mechanism of theapparatus of this invention. As in the construction shown in ourprevious application No. 5,601/66 the spiking mechanism comprises aspiked roller and a backing roller. However, in this case instead ofbeing arranged to spike the strip after the tube is formed, as in thepreferred embodiment shown in our prior application, the mechanism ishere arranged to spike the strip before it is convoluted about themandrel. The backing roller 36 is mounted on the machine frame in frontof the initial forming roller 16 and the spiking roller 37 is mountedabove it on an axle 38 carried by a bracket 39 pivoted on a pivot pin 41of the frame section 42 which carries the backing roller 36. The bracket39 is connected at its upper end to a ram and cylinder mechanism 43which can be operated to pivot the bracket about the pivot 41 andthereby move the spiking roller 37 toward or away from the strip torender it operative or inoperative or to vary the degree of penetrationof the spikes thereby varying the sizes of the holes formed.

FIG. 17 shows a modification of the forming head for forming the seam bythe first of the above-mentioned alternative methods. FIG. 18 shows thesteps in the formation of the seam by this method. In this method thestrip is formed at one edge with a L-shaped-flange 51 and in the otheredge with a U- shaped channel element 52 the channel element in thiscase being formed such that its open mouth is inwardly directed withrespect to the formed tube. As the strip is fed to the mandrel theL-shaped flange 51 is mated with the channel element 52 and as the strippasses around the mandrel it passes between nipping-in rollers 53 whichnip-in the base of the channel to partially close its mouth as shown atA in FIG. 18. As the seam passes further around the mandrel it isfinally flattened by the fonning rollers 21, 22 as in the previousconstruction. The steps in the formation of the seam by the secondalternative method are shown diagrammatically in FIG. 19. In this methodthe edges of the strip are formed so that in one edge there is a pair ofribs 61, 62 which are outwardly directed with respect to the tube and inthe other edge there is a pair of channels 63. 64 formed with theirmouths facing inwardly with respect to the tube. As the strip isconvoluted about the mandrel the ribs 61, 62 are first mated with thechannels 63, 64 as shown at A in FIG. 19. The channels are next spreadapart as shown at B in FIG. 19 and finally they are flattened down toform oppositely directed channels with the arms of the flange 61. 62locked within them as shown at C in FIG. 19.

It will be seen with the resultant seam formed by either of the methodsof FIGS. 18 and 19 is the same and also that the seam is substantiallythe same as that formed by the method illustrated with reference to FIG.9 of the drawings except that in the latter case the body of the seamlies within the tube whereas in the two former cases the body of theseam lies on the outside of the tube. Also in the construction shown inFIG. 9 each arm of the flange is of double thickness since it is formedfrom an element which is originally channel shaped whereas in theconstructions shown in FIGS. 18-19 the free arm of the flange is ofsingle thickness the flange having been formed from an original L-shapedelement. It would be readily apparent however that the double thicknessportion can easily be omitted from the construction shown in FIG. 9 andlikewise that the free arm of the flange shown in FIGS. 18 and 19 can beof double thickness rather than single thickness.

The seam according to this invention and its method of formation haveenabled us to produce apparatus in which the substitution of one mandrelfor another when a different-sized tube is to be produced can be carriedout relatively simply. This is illustrated in FIG. of the drawings whereillustrations (a), (b) and (c) show medium-sized, small-sized andlarge-sized mandrels respectively which can all be secured to the samebasic forming head 17 in a simple operation. That this can be done isdue to the fact that the formation of the seam is carried out at onlytwo locations about the periphery of the mandrel. At the first locationa pair of forming rollers (such as those shown as 21 and 22 in FIGS. 7and 8) are mounted on the machine frame and are common to all sizes ofmandrel. The forming means at the second location comprise the angleddeforming rollers 23 and the surface of the mandrel itself oralternatively the backing roller 20 (see FIG. 8). The

deforming rollers 23 are carried on the bracket 70 which is bolted tothe mandrel l8 and the mandrel 18 itself is secured to the frame 71 ofthe coiling head by means of bolts 72.

It will thus be seen, particularly by reference to FIG. 20, that tochange from one sized mandrel to another all that is necessary is toundo the bolts 72. remove the existing head and substitute a new one.Since the roller 21 is located within the cavity 73 in the mandrel butis not attached to the mandrel it, and its cooperating roller 22, willnot be disturbed by this changeover operation. It is thus possible inthe construction according to this invention to change from one mandrelsize to another merely by changing the mandrel and its associatedforming rollers (such as 23) without the necessity for any adjustment ofthe other forming means 21, 22.

The seam and the method of apparatus for its construction provided bythis invention provides a strong and reliable seam and one which can bemade on apparatus in which the substitution of one forming head foranother can readily and rapidly be carried out without the complicatedand delicate adjustment of the forming means which was necessary in theconstruction according to our prior application No. 5,601/66. It willalso be seen that according to this invention the major proportion ofthe seam-forming operation is carried out before the strip reaches themandrel. The apparatus is accordingly more easily and readily controlledand adjusted than was the case in the previous construction.

We have described above a number of alternative methods for theformation of the seam according to this invention and also a number ofmodifications which may be made to the apparatus for the construction ofthe seam. It will be appreciated however that other variations andmodifications could be made to the method and apparatus within the scopeof the invention as defined by the following claims.

Iclaim:

1. A tube formed from helically wound ductile strip material withadjacent edges of the strip joined together by a locked seam whereinsaid locked seam comprises a pair of generally oppositely directedchannels formed in one edge of said strip and disposed on opposite sidesof a longitudinal medial plane of the seam with their mouths facing, anda complementary flange of generally T-shaped cross section formed in theother edge of said strip with its arms disposed one within each of thesaid channels.

2. A tube as claimed in claim 1, wherein the channels are directlyfacing one another and the arms of the flange are sub stantiallycoplanar.

3. A tube as claimed in claim 1, wherein the channels are disposed toface slightly outwardly of the tube and their directions of facingintersect at an included angle slightly less than the arms of theflanges being correspondingly angled.

4. A tube as claimed in claim I wherein the shank of the flange liesapproximately on a longitudinal medial plane of the seam and is disposedtransverse of the elongate dimension of the tube.

5. A tube as claimed in claim 2 wherein the shank of the flange liesapproximately on a longitudinal medial plane of the seam and is disposedtransverse of the elongate dimension of the tube.

6. A tube as claimed in claim 3 wherein the shank of the flange liesapproximately on a longitudinal medial plane of the seam and is disposedtransverse of the elongate dimension of the tube.

* a x a

1. A tube formed from helically wound ductile strip material with adjacent edges of the strip joined together by a locked seam wherein said locked seam comprises a pair of generally oppositely directed channels formed in one edge of said strip and disposed on opposite sides of a longitudinal medial plane of the seam with their mouths facing, and a complementary flange of generally Tshaped cross section formed in the other edge of said strip with its arms disposed one within each of the said channels.
 2. A tube as claimed in claim 1, wherein the channels are directly facing one another and the arms of the flange are substantially coplanar.
 3. A tube as claimed in claim 1, wherein the channels are disposed to face slightly outwardly of the tube and their directions of facing intersect at an included angle slightly less than 180*, the arms of the flanges being correspondingly angled.
 4. A tube as claimed in claim 1 wherein the shank of the flange lies approximately on a longitudinal medial plane of the seam and is disposed transverse of the elongate dimension of the tube.
 5. A tube as claimed in claim 2 wherein the shank of the flange lies approximately on a longitudinal medial plane of the seam and is disposed transverse of the elongate dimension of the tube.
 6. A tube as claimed in claim 3 wherein the shank of the flange lies approximately on a longitudinal medial plane of the seam and is disposed transverse of the elongate dimension of the tube. 